1. Description of the Art
Micro-encapsulation techniques are increasingly being utilized in such diverse areas as drug delivery systems, cosmetics, agricultural, chemical, and food industries to enhance the effectiveness of a particular component at the lowest possible cost. Generally, microcapsule drug delivery systems are intended for oral, inhalation parenteral, ocular, or topical use. The release of orally administered medications may occur in the oral cavity such as for buccal or sublingual administration, or may occur in the gastrointestinal tract after the oral dosage form is swallowed. There are, for example, capsules and tablets that contain microcapsules to release the drug in the stomach, enteric-coated formulations that release the medication in the intestinal tract of the patient, and controlled release dosage capsules that release the drug in both the stomach and the intestines. Some microcapsules release drug in the lower intestinal tract including the colon. The profile and kinetic pattern governing the release rate of an entrapped active component from a microcapsule depends on the nature and morphology of the shell material encapsulating the active component, and formulation ingredients within the core and the shell material. Further, many individuals suffer from chronic health problems that require the regular administration of medicaments. Diseases such as diabetes, allergies, epilepsy, heart problems, AIDS, and even cancers require the regular delivery of precise doses of medicaments if patients are to survive over long periods of time.
Unfortunately, conventional oral dosage forms suffer from a number of disadvantages. Typically, to effectively handle and dispense small doses a considerable amount of adjuvant material must be added in order that the final dosage form is of a manageable size. Thus, typical methods for manufacturing include the mixing of the pure drug with various other substances commonly referred to as excipients or diluents that are therapeutically inert and acceptable by regulatory bodies, such as the Federal Drug Administration (FDA). Many if not most micro-encapsulation techniques generate a broad distribution of microcapsule sizes. The broad distribution in microcapsule size makes it more difficult to accurately dispense an optimal drug dosage. In addition, it produces greater variability in dissolution rates and, thus, decreases the control over the absorption rate of the drug in the body. In addition, there is an increasing need to control the drug absorption process to sustain adequate and effective drug levels over a prolonged time period.
The availability of useful drug delivery systems that provide an optimal drug dosage to be delivered to a particular site in the body by means of microcapsule dosage forms is very limited. The ability to control and extend the release of an active component from a microcapsule without adversely modifying the structure or normal biological function of the active component in the body after administration and absorption is also extremely limited today. If these problems persist, many new and potentially life saving beneficial drugs will either be impractical or have limited effectiveness in the dosage forms currently available. As the demands for more efficient and lower cost drugs continues to grow, the demand to develop systems or drug carriers capable of delivering the active molecules specifically to the intended target organ, while increasing the therapeutic efficacy will continue to increase as well.